1. Nonavian Diapsid Amniotes
Reptiles
Nonavian Diapsid Amniotes

2. Taxonomy Kingdom: Animalia Phylum: Chordata Subphylum: Craniata
Infraphylum: Vertebrata
Class: Reptilia

3. Evolutionary Adaptations
Evolved ~ 350 mya
Able to live on land….thanks to the amniotic egg
Amniotic Egg
Extraembryonic membranes to…
Protect the embryo from desiccation (drying out)
Cushion the embryo
Promote gas transfer
Store waste materials
Leathery or hard shells for protection
Albumen for cushion, moisture, & nutrients
Yolk supplies the food

4. Reptile Adaptations to… Life on Land
Amniotic Egg
Impervious skin
Horny nails- used for digging & locomotion
Water-conserving kidneys
Enlarged lungs
Loss of lateral-line system

5. Reptile Characteristics
Thick, dry, & keratinzed skin (covered in scales)
May secrete pheromones through their skin for sex recognition & defense
Shed their skin (ecdysis)
Due to low blood flow to the outer layer of skin
Skin may be colored for sex recognition, mimicry, and for cryptic purposes

6. Reptile Characteristics
Skeleton:
Longer skull- development for breathing and better smell
More cervical vertebrae for head movement
Ribs modified
Fused to create the shell in turtles
Muscular connections for movement in snakes
Tail vertebrae may possess a fracture plane
Can break their tail off when threatened

7. Reptile Characteristics
Nutrition & Diet
Carnivores
Except turtles (may be carnivores, herbivores, or omnivores)
May have sticky tongues for catching prey
May extend the length of their body
Skull and jaw bones may spread apart to allow room for bigger prey

8. Reptile Characteristics
Circulation, Gas Exchange, & Temperature Regulation
3 chambered heart
2 atria & 1 ventricle
Ventricle is partially divided (completely divided in crocodiles)
Breathe with lungs
Thermoregulate with external heat sources (ectothermic)
Tend to bask in sunlight for warmth

9. Reptile Characteristics
Nervous System
Developed brain
Vision is the dominant sense
Upper & lower eyelids and nictitating membrane
May detect light with a median (parietal) eye
Jacobson’s (vomeronasal) organs- olfactory organs
Connected to the forked tongues in snakes

10. Reptile Characteristics
Reproduction & Development
Dioecious
Internal fertilization
Sex organs contained inside of the cloaca
Courtship behavior is species specific
Mother abandons eggs after she lays them
Alligator nest temperature determines gender of young
<31.5C= females
C= males
32 C= males & females

11. Class: Reptilia Order: Testudines
Carapace
Turtles
Characteristics:
Bony shell
Limbs articulating internally to the ribs
Keratinized beak rather than teeth
Shell
Dorsal=carapace
Ventral=plastron
Plastron

12. Class: Reptilia Order: Testudines
North American box turtle
Shell has hinges to allow the anterior & posterior regions to raise up or down
The shell closes when the turtle pulls in it’s head & tail

13. Class: Reptilia Order: Testudines
Long life spans
Large tortoises live >100 years
Reach sexual maturity between 7 & 8 years
Oviparous- lay eggs
Females dig out nests in the soil
Cover the eggs with soil
Eggs take 4 weeks to 1 year to develop
Young are independent from parents (no parental care)

14. Class: Reptilia Order: Testudines
Turtles vs. Tortoises
Turtles- aquatic & have webbed feet
Tortoises- terrestrial & do not have webbed feet
Conservation
Turtles are vulnerable due to…
Slow growth rates
Long juvenile periods
Nearing extinction thanks to young turtle predators & turtle hunters

15. Class: Reptilia Order: Crocodylia
Alligators, crocodiles, gavials, & caimans
Derived from archosaurs (ancient reptiles)
Triangular eye orbits
Laterally compressed teeth
Mildly evolving over the past 170 my
Nostrils are at the tip of the snout (can breathe while mostly submerged)
Muscular & elongated tail
Swimming, offense, defense, & attacking prey
Swallow food whole
Oviparous & take care of their young

16. Class: Reptilia Order: Squamata
Lizards
2 pairs of legs
Upper & lower jaws unite anteriorly
Geckos- nocturnal & can vocalize with clicking sounds
Iguanas- can glide from a tree for at least 30 m
Chameleons- arboreal & consume insects
Change color in response to illumination, temperature, & behavioral state
Gila monster- venomous lizard
Southwest U.S.
Venom released when they chew (not fatal to humans)

17. Class: Reptilia Order: Squamata
Snakes
2,900 species (300 are venomous…not poisonous!!!)
Scale patterns can determine whether the snake is venomous or not
30,000 people die a year from snake bites (mostly in SE Asia)
Only 9-15 die from snake bites each year in the U.S.
Long & lack limbs
May contain more than 200 vertebrae
May swallow large prey whole (movable jaw)

18. Class: Reptilia Order: Squamata
Worm Lizards
Live in the soils of Africa, South America, the Caribbean, & the Mideast
Legless
Single median tooth in the upper jaw
Ringlike folds in the skin (annuli)
Easily move forwards or backwards